Thursday, March 29, 2018

[Entomology • 2017] Evolutionary Assembly of Communities in Butterfly Mimicry Rings

in Joshi, Prakash & Kunte, 2017.

 Species co-occurrence in ecological communities is thought to be influenced by multiple ecological and evolutionary processes, especially colonization and competition. However, effects of other interspecific interactions and evolutionary relationships are less explored. We examined evolutionary histories of community members and roles of mutualistic and parasitic interactions (Müllerian and Batesian mimicry, respectively) in the assembly of mimetic butterfly communities called mimicry rings in tropical forests of the Western Ghats, India. We found that Müllerian mimics were phylogenetically clustered, sharing aposematic signals due to common ancestry. On the other hand, Batesian mimics joined mimicry rings through convergent evolution and random phylogenetic assembly. Since the Western Ghats are a habitat island, we compared species diversity and composition in its mimicry rings with those of habitat mainland to test effects of biogeographic connectivity. The Western Ghats consisted of fewer mimicry rings and an overall smaller number of aposematic species and mimics compared to habitat mainland. The depauperate mimicry rings in the Western Ghats could have resulted from stochastic processes, reflecting their long temporal and spatial isolation and trickling colonization by the mimetic butterfly communities. These results highlight how evolutionary history, biogeographic isolation, and stochastic colonization influence the evolutionary assembly and diversity of ecological communities.

Keywords: phylogenetic community ecology, community dynamics, island biogeography, Batesian mimicry, Müllerian mimicry.


Figure 1. Mimicry rings in the Western Ghats, India, showing spatial and temporal overlap between Batesian mimics and aposematic species and their mimicry phenotypes. Each mimicry ring is named after the predominant species or genus of aposematic species. In the phenological tables, J–D represent months in a year; monthly occurrence of aposematic species and Batesian mimics are shown in green, and absence is shown in white; and in each mimicry ring, aposematic species are listed before Batesian mimics, separated by a black line. Most aposematic species and Batesian mimics overlap in time. The distributional maps on the outline of the Western Ghats show spatial overlap between aposematic species and Batesian mimics. Green areas represent distributions of aposematic species, where darker green areas show more restricted distributions of one or more aposematic species when multiple aposematic species exist in mimicry rings. Black spots on these maps show distributions of Batesian mimetic species, with yellow spots representing narrower distributions of some of the Batesian mimetic specie. Distributional ranges of Batesian mimics are embedded within the distributional ranges of aposematic species, signifying ecological dependence of Batesian mimics on the presence of aposematic species.

Jahnavi Joshi, Anupama Prakash and Krushnamegh Kunte. 2017. Evolutionary Assembly of Communities in Butterfly Mimicry Rings. The American Naturalist. 189(4); E58-E76.  DOI:  10.1086/690907

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